fix Brave crash on confirm(1) bug
fix Brave crash on confirm(1) bug

- make sure that when `message` is a  number (or other non-string type) it is coerced to a string
- same change as what @bridiver did for alerts in #4798, but for confirm dialog

fixes #4883

willy-b/browser-laptop,darkdh/browser-laptop,Sh1d0w/browser-laptop,darkdh/browser-laptop,pmkary/braver,jonathansampson/browser-laptop,diasdavid/browser-laptop,willy-b/browser-laptop,diasdavid/browser-laptop,pmkary/braver,diasdavid/browser-laptop,Sh1d0w/browser-laptop,timborden/browser-laptop,dcposch/browser-laptop,pmkary/braver,jonathansampson/browser-laptop,jonathansampson/browser-laptop,luixxiul/browser-laptop,dcposch/browser-laptop,dcposch/browser-laptop,luixxiul/browser-laptop,dcposch/browser-laptop,Sh1d0w/browser-laptop,luixxiul/browser-laptop,willy-b/browser-laptop,luixxiul/browser-laptop,darkdh/browser-laptop,willy-b/browser-laptop,diasdavid/browser-laptop,darkdh/browser-laptop,timborden/browser-laptop,timborden/browser-laptop,pmkary/braver,jonathansampson/browser-laptop,timborden/browser-laptop,Sh1d0w/browser-laptop